MIL-STD 810, Method 516, Shock Testing Overview

MIL-STD 810, Method 516, Shock Testing Procedure I – Functional Shock

MIL-STD 810, Method 516, Shock Testing Procedure II – Transportation Shock

MIL-STD 810, Method 516, Shock Testing Procedure III – Fragility

MIL-STD 810, Method 516, Shock Testing Procedure IV – Transit Drop

Crash hazard shocks apply to materiel mounted in air or ground vehicles.  Shock testing according to Procedure V of MIL-STD 810, Method 516 is intended to test the strength of products during a crash situation to verify that parts do not break apart, eject and become a safety hazard.  Failures of this nature could cause dangerous projectiles that could impact occupants or create significant damage to the vehicle.

This article will focus on the shock test condition when measured field data is not available and the testing will use classical shock impulses.  The terminal peak sawtooth is the default classical shock pulse to be used for this condition.  Figure 516.7-10 from MIL-STD-810 shows its shape and tolerance limits.  Table 516.7-IV contains the terminal peak sawtooth default test parameters for Procedure V – Crash Hazard Shock.  In limited cases a half sine shock impulse is specified.  Its shape and tolerance limits are shown in Figure 516.7-12.

Figure 516.7-10. Terminal peak sawtooth shock pulse configuration and its tolerance limits

Table 516.7-IV. Terminal peak sawtooth default test parameters for Procedure V – Crash Hazard Shock

Figure 516.7-12. Half-Sine shock pulse configuration and tolerance limits

The product should be mounted to the machine or fixture as it would in normal use.  So if it is bolted using a flange, then it should be attached to a fixture using this flange with the same size and number of bolts.

Typically, calibration shocks are performed first using a mass similar in size, weight and center of gravity (CG) of the product to be tested.  Once the desired shock requirements are met with the calibration mass, the mass is removed and the product to be tested is installed on the shock test machine or fixture.  The units under test do not have to be operating during crash hazard shocks.  After each shock, the test sample is inspected for visual damage.  Minor permanent deformations are usually acceptable as long as the product stays intact.  Significant damage such as large cracks may be cause for failure if they pose a risk of structural failure.

The most common requirement is to perform 2 shocks along both the positive and negative directions along 3 orthogonal axes.  This is a total of 6 directions and 12 total shocks.  When setting up to perform shocks in each direction, calibration shocks with the mass simulant are performed first because the weight, CG and product response could require different settings on the shock machine.  The shocks are performed along both the positive and negative directions of each axis because classical shocks are single polarity.

For more information on Shock Testing or other testing services, contact DES or call 610.253.6637.

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MIL-STD 810, Method 516, Shock Testing Overview

MIL-STD 810, Method 516, Shock Testing Procedure I – Functional Shock

MIL-STD 810, Method 516, Shock Testing Procedure II – Transportation Shock

MIL-STD 810, Method 516, Shock Testing Procedure III – Fragility

Method 516, Procedure IV is for testing products that could be accidently dropped such as when they are removed from a shelve or dropped when handling.  The test item is physically dropped onto a hard surface to produce the shock.  Products can be tested inside their transit case or unpackaged.  Typically, they would be tested in the configuration that is normally used for transportation, handling, or a combat situation.

The default drop test conditions are contained in Tables 516.7-VII through 516.7-IX from MIL-STD-810G w/Change 1.  They are meant to represent typical drop events that an item might experience from the time it is shipped from its manufacturer to the end of its service life.  Table 516.7-X and Figure 516.7-15 from MIL-STD-810G w/Change 1 show the standard drop orientations.  Figure 516.7-16 shows typical edge and corner drop configurations for large packages as discussed in Notes 2-4 of Table 516.7-VII.

If practical, the product should be periodically visually inspected and/or operationally checked during the drop test.  After completion of all of the drop events, typically a full visual inspection and operational check is performed.

DES has performed many product or package drop tests.  For more information on Shock Testing or other testing services, contact DES or call 610.253.6637.

Table 516.7-VII. Logistic transit drop test¹

Table 516.7-VIII. Tactical transport drop test

Table 516.7-IX. Severe tactical transport drop test

Table 516.7-X. Five standard drop test orientations

Figure 516.7-15. Standard drop orientations for rectangular and cylindrical packages

Figure 516.7-16. Illustration of edge drop configuration

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• MIL-STD 810, Method 516, Shock Testing Overview 
• MIL-STD 810, Method 516, Shock Testing Procedure I – Functional Shock
• MIL-STD 810, Method 516, Shock Testing Procedure II – Transportation Shock

Procedure III is used to determine what shock conditions will cause a product to stop operating, degrade or fail.  The shock magnitudes are systematically increased until a problem occurs.  This procedure can be also performed using environmental temperature conditioning.

This article will assume that the fragility shocks expected to be encountered by the product are not complex transients.  Therefore, the trapezoidal classical shock pulse, as defined in Figure 516.7-11 and Table 516.7-V from MIL-STD-810, Method 516 would be used for Fragility testing.

Figure 516.7-11. Trapezoidal shock pulse configuration and tolerance limits (for use when shock response spectrum analysis capability is not available in Procedure III – Fragility)

Note 1: Am is dependent upon drop height “h.”

Note 2: “h” is the drop height in SI: m (in) and g=9.81 m/s2(386.09 in/sec2)

Table 516.7-V. Trapezoidal pulse parameters

T_D corresponds to the period of the first mounted natural frequency of the item.  During fragility testing, T_D is held constant.  Determination of the fragility level is accomplished by starting at low levels of shock magnitude (A_m) and then proceeding to increase the shock magnitude until:

1. Failure or degradation of the unit occurs.
2. A predefined test goal is reached without failure of the unit under test.
3. A critical level of shock is reached whereby increasing the magnitude will cause a failure at a higher level of shock.

An analysis of the product should be performed prior to testing to:

• estimate its anticipated fragility level
• establish a low starting shock level
• estimate the first mode mounted frequency of the materiel in order to specify the pulse duration T_D.

The product is normally tested in an un packaged, non-operational condition.  The typical procedure when using the trapezoidal classical shock pulse is to first perform calibration shocks using a mass similar in size, weight and center of gravity (CG) of the unit to be tested.  Once the desired shock requirements are met with the calibration mass, the mass is removed and the product to be tested is installed on the shock test machine or fixture.

Operation of the test item and inspection for visual damage is performed before/after each shock.  If testing along more than one axis is required, then testing in the next axis should be completed before proceeding to the next higher shock magnitude.

For more information on Shock Testing or other testing services, contact DES or call 610.253.6637.

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MIL-STD 810, Method 516, Shock Testing Overview

Shock testing according to Procedure I of MIL-STD 810, Method 516 is intended to test products while they are operating to see if any functional problems occur and to determine if they survive without damage.  The applied shocks usually represent those that may be encountered during operational service.  This article will focus on the shock test condition when measured field data is not available and the testing will use classical shock impulses.  The terminal peak sawtooth is the default classical shock pulse to be used for this condition.  Figure 516.7-10 from MIL-STD-810 shows its shape and tolerance limits.  Table 516.7-IV contains the terminal peak sawtooth default test parameters for Procedure I -Functional Test.  In limited cases a half sine shock impulse is specified.  Its shape and tolerance limits are shown in Figure 516.7-12.

The product should be mounted to the machine or fixture as it would in normal use.  So, if it is bolted using a flange, then it should be attached to a fixture using this flange with the same size and number of bolts.

The typical shock testing procedure is to first perform calibration shocks using a mass similar in size, weight and center of gravity (CG) of the product to be tested.  Most commonly a non-working mechanical product is used for this purpose.  Once the desired shock requirements are met with the calibration mass, the mass is removed and the product to be tested is installed on the shock test machine or fixture.  Since this is a functional shock, the product must be operating and monitored for anomalies.   Therefore, before the shock is applied, the product must be energized and the monitoring equipment should be operating.  After each shock, operation of the test item is verified and it is inspected for visual damage.

The most common requirement is to perform 3 shocks along both the positive and negative directions along 3 orthogonal axes.  This is a total of 6 directions and 18 shocks.  When setting up to perform shocks in each direction, calibration shocks with the mass simulant are performed first because the weight, CG and product response could require different settings on the shock machine.  The shocks are performed along both the positive and negative directions of each axis because classical shocks are single polarity.

For more information on Shock Testing or other testing services, contact DES or call 610.253.6637.

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MIL-STD-810 is a public military test standard that is designed to assist in the environmental engineering considerations for product design and testing.  For the purposes of this blog series we will focus on Method 516.7, Shock Testing.

The purpose of shock testing is to:

1. Evaluate if a product can withstand shocks encountered in handling, transportation, and service environments
2. Determine the product’s fragility level
3. Test the strength of devices during a crash situation to verify that parts do not break apart, eject and become a safety hazard

Shock testing failures are a function of the amplitude, velocity, and the duration of the impulse.  If a product has a resonance frequency that corresponds with the frequency of the shock, the effects of the shock will be magnified.

Typically shocks in Method 516.7 are limited to a frequency range not to exceed 10,000 Hz, and a duration of not more than 1.0 second.  Method 516.7 contains eight test procedures which are summarized in Table 516.7-I.

Table 516.7-I from MIL-STD-810G w/Change 1

The differences among procedures is briefly defined below:

1. Procedure I – Functional Shock. Procedure I is intended to test products while they are operating to see if any functional problems occur and to determine if they survive without damage. The applied shocks usually represent those that may be encountered during operational service.
2. Procedure II – Transportation Shock. Procedure II is used to evaluate products for repetitive shocks from transportation environments. This procedure typically uses a classical terminal peak sawtooth impulse to simulate transportation shocks.
3. Procedure III – Fragility. Procedure III is used to determine what shock conditions will cause a product to stop operating, degrade or fail. The shock magnitudes are systematically increased until a problem occurs.  This procedure can be also performed at environmental temperature extremes.
4. Procedure IV – Transit Drop. This procedure is used to test items that could be accidentally dropped such as when they are removed from a shelve or dropped when handling. The test item is physically dropped onto a hard surface during Procedure IV.  The items can be tested inside their transit case or unpackaged.
5. Procedure V – Crash Hazard Shock Test. Procedure V is used to test materiel mounted in air or ground vehicles. This procedure is intended to verify that parts do not beak loose which would cause a hazard to occupants or create significant damage to the vehicle.
6. Procedure VI – Bench Handling. This procedure is used to test products that may experience shocks on a work bench. Bench handling shocks could occur when items are being repaired or when they are in the process of being packaged.  The products are tested in an unpackaged configuration.  The drop heights are less than Procedure IV.

Procedures VII and VII are very specialized shock tests.  They are briefly mentioned because they are part of Method 516.7, Shock Testing.

1. Procedure VII – Pendulum Impact. Procedure VII is intended to test the ability of large shipping containers and their internal contents to resist horizontal impacts from accidental handling.
2. Procedure VIII – Catapult Launch/Arrested Landing. Procedure VIII is intended for materiel mounted in or on fixed-wing aircraft that is subject to catapult launches and arrested landings.

The laboratory shock test options are summarized below in Table 516.7-II.  The shock test options are divided according to the use of Time Waveform Replication (TWR), drop tests, classical shock pulses, or SRS shocks.  TWR is considered to be superior and the most realistic as it is based upon direct replication of field measured data, however it is not usually available.  Classical shock pulses are used when TWR data is unavailable.  Shock Response Spectra (SRS) refers to cases in which an SRS curve is used for the test specification.

Table 516.7-II – Laboratory Shock Test Options from MIL-STD-810G w/Change 1

TWR – Time Waveform Replication

Drop = free fall drop event

SRS = Shock Response Spectra

X_tp – terminal peak sawtooth classical shock

X_trap – symmetric trapezoidal classical shock

X_sin – two-second damped (Q=20) sine burst

Note (1)- Horizontal Impact

It is important that the shock data acquisition instrumentation is adequate to capture the shock impulse.  Method 516.7 provides guidelines for the shock test data acquisition system.

To learn more about our shock testing services, please feel free to contact us with your inquiry. Feel free to explore our site to learn about our full line of product testing services, and the test standards that we can help our clients with.

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